Function validate_regex

src/black/__init__.py:245–253

(
    ctx: click.Context,
    param: click.Parameter,
    value: str | None,
)

def validate_regex(
    ctx: click.Context,
    param: click.Parameter,
    value: str | None,
) -> Pattern[str] | None:
    try:
        return re_compile_maybe_verbose(value) if value is not None else None
    except re.error as e:
        raise click.BadParameter(f"Not a valid regular expression: {e}") from None


@click.command(